Thermosetting plastic materials, including many elastomers, are generally difficult to recycle due to an inability to efficiently melt or degrade the material. Thus, to make effective use of scrap thermosetting materials, such as used vehicle tires, efforts have been made to mechanically reprocess the scrap material into a useful recycled material.
For instance, one approach to recycle materials, such as thermosetting plastic materials, is to grind, pulverize or crush the scrap materials into relatively fine particles which are suitable for re-use in tires and other applications. In this regard, the use of screw-type extrusion devices has been proposed to meet this need.
Unfortunately, with respect to many of the above known apparatus, limitations are imposed due to their construction. For instance, screw-type extrusion devices tend to simply transport significant amounts of scrap material down a screw with little or no reduction in scrap particle size or character. Thus, additional passes are necessary, which tend to decrease operating efficiency. Further, the configurations of many of the apparatus fail to readily permit the passage of relatively hard fabric or wire fragments commonly encountered in reinforced elastomeric materials, such as is found in belted tires. As a result, the relatively hard fabric or wire fragments tend to damage the grinding elements, such as the screw threads of the extrusion device, and other machine surfaces of such apparatus.
Alternatively, grinders can be used that grind scrap materials by cutting or chipping operations. However, the resulting particles tend to have smoothly cut surfaces of relatively low surface area. The particles are thus of limited useful value.
Finally, some apparatus grind scrap materials by repetitive grinding in a series of refining mills. For grinding scrap tires, these apparatus would shred tire cords into short finely dispersed filaments, which are then separable from ground scrap rubber. However, considerable difficulty in separation is commonly encountered.
As used herein, the term "transfergrinder device" refers generally to a device, of the type commonly referred to as transfermix devices, which is suitable for mixing a raw or uncured feed material. "Feed Material", as used herein, may refer to any material for which grinding is desired. In particular, the feed materials contemplated to be ground by the present transfergrinder device include plastics (particularly reinforced elastomerics), ceramics, wood or mixtures thereof. Finally, as denoted herein like reference numerals refer to like parts.